Setting the scene
The Democratic Party split over slavery, fielding Northern and Southern nominees, while the Constitutional Union Party offered a fourth candidate. Republican Abraham Lincoln, a former one-term congressman from Illinois, opposed expanding slavery into territories but did not campaign in the South.
What happened
Lincoln won the November 1860 election with about 39.8 percent of the popular vote and 180 electoral votes, carrying every free state except New Jersey. He received not a single electoral vote from a future Confederate state.
Why it still matters
South Carolina seceded in December 1860; six more states followed before Lincoln's March 1861 inauguration, and Fort Sumter fell in April, opening the Civil War. Memorable detail: Lincoln did not appear on the ballot at all in ten Southern states, making his victory there mathematically impossible.
Background
He won without any Southern electoral votes.